This application claims priority of Korea patent Application No. 10-2000-0065840, filed on Nov. 7, 2000.
(a) Field of the Invention
The present invention relates to a method for providing engine torque information, and more particularly, to a method for providing more accurate engine torque information to control means other than an ECU.
(b) Description of the Related Art
Generally, an ECU of an automobile, when providing torque information to other control means, provides a throttle angle of an engine or an intake manifold pressure, and therefore other control means must calculate torque with reference to the provided torque information.
For example, a conventional ECU provides the throttle angle or the intake manifold pressure to transmission control means, rather than a calculated torque.
Because the ECU is always detecting the throttle angle and the intake manifold pressure, it is easy for the ECU to acquire these data and thus provide them to other control means.
However, because the ECU provides information by which torque can be calculated rather than a calculated torque, aberrations of the information necessarily becomes great. The engine torque is quite affected by air-fuel ratio and ignition timing. Therefore, if torque is calculated based on the throttle angle or the intake manifold pressure, the influences of air-fuel ratio and ignition timing are neglected, and thus calculated torque is not correct.
Also, because fairly precise torque information should be exchanged with a motor control means in a parallel hybrid car in which an engine and a motor are directly connected, approximate torque information is not sufficient. However, the prior art can""t provide sufficiently precise engine torque information.
The present invention has been made in an effort to solve the above problems. It is an object of the present invention to provide a method for providing accurate engine torque information in a present driving state to other control means.
To achieve the above object, the method for providing engine torque information according to the present invention comprises the steps of:
(a) obtaining an optimal ignition timing from a chart of RPM points and an amount of air intake;
(b) obtaining a revised optimal ignition timing by adding amounts of ignition timing changed by a present coolant temperature and a present air-fuel ratio to the optimal ignition timing obtained in step (a);
(c) calculating a difference between the revised optimal ignition timing obtained in step (b) and real ignition timing at a present driving state;
(d) obtaining an ignition efficiency value by using the difference calculated in step (c);
(e) obtaining basic indicated torque from a chart at a present driving state, and then calculating a revised present indicated torque by multiplying the basic indicated torque by the air-fuel ratio efficiency and the ignition efficiency value obtained in step (d), the revised present indicated torque being equal to maximum torque of an engine;
(f) calculating real engine torque by subtracting friction torque from the revised present indicated torque; and
(g) providing the real engine torque calculated in step (f) to other control means.